sanic_chat_server.py

import asyncio

from sanic import Sanic
from sanic.websocket import ConnectionClosed


app = Sanic(__name__)

ws_clients = set()


async def broadcast(message):
    global ws_clients
    broadcasts = [ws.send(message) for ws in ws_clients]
    for result in asyncio.as_completed(broadcasts):
        try:
            await result
        except ConnectionClosed:
            pass


@app.websocket("/ws")
async def websocket(_, ws):
    global ws_clients
    ws_clients.add(ws)
    while True:
        try:
            message = await ws.recv()
        except ConnectionClosed:
            ws_clients.remove(ws)
            break
        else:
            await broadcast(message)


if __name__ == '__main__':
    app.run(host="0.0.0.0", port=8000, debug=True)